This thesis aimed to address fundamental study and related applications of covalent adaptable networks (CANs), focusing on polyimine materials. Crosslinked polyimine represents a novel class of covalent adaptable network, which exhibits room temperature repairability, catalyst-free malleability, recyclability, and robust mechanical properties. Polyimine network prepared from commercially available monomers (terephthaldehyde, diamine and triaminotriethylamine) have been investigated including solvent and concentration effect on their physical properties. Monomer concentration and solvent properties directly control reaction rates and influence solvent diffusion into polymer chains and interfacial interactions during the polymerization progress, a range of mechanical properties can be obtained in different solvents from the same monomer composition, thus determining the morphology evolution and properties of polymers. Fully rehealable and recyclable electronic skin by introducing silver nano-particles into polyimine networks has been designed based on polyimine materials. Such electronic skin has tactile, flow, temperature, and humidity sensing capabilities. Full recyclability has been demonstrated by simply soaking the whole device in one of the starting monomer at room temperature even without any stirring.